“I will surely bless you and make your descendants as numerous as the stars in the sky and as the sand on the seashore.”
Yet, Israel became and remains one of the smallest nations in the world. Surely the Children of Abraham are not limited to the Israelites. Even at the original time that God introduced the covenant of circumcision, Abraham’s entire household was circumcised, including his servants and all other males not born to him. So clearly, the covenant was not being made just for his descendants, but for all who declared the same faith that Abraham declared.
The apostle Paul reiterated this in his letter to the new believers in Rome; that the “Children of Abraham” are the children of the promise.
And, more importantly, this was something that John the Baptist was preaching:
“Produce fruit in keeping with repentance. And do not begin to say to yourselves, ‘We have Abraham as our father.’ For I tell you that out of these stones God can raise up children for Abraham.”
…and what Jesus later reiterated, that just being a physical descendant of Abraham (a Jew), wasn’t enough to be saved
In the same way, even as believers, we cannot save our children by circumcision, either in the flesh or by the waters of baptism. Only Jesus Christ can save them when they declare their faith as their own. Our faith in Christ cannot save them. Just because we are children of the promise, our children do not become automatic heirs. They must humble themselves, submit themselves to the throne of God via the foot of the Cross, and receive the promise through their own faith.
Some churches use examples described in the book of Acts to justify infant baptism, saying that the phrase “entire household” includes the children of that household. Except that biblically, children are excluded from the counting of any numbers (except when explicitly identified) because they are not “of age” until age 13. In these cases, only the reasonable assumption that children ages 13 and up could be included in the entire household.
This same theology is often used in conjunction with Jesus’ statement of “Let the little children come to me, and do not hinder them, for the Kingdom of God belongs to such as these”
At that time Jesus said, “I praise you, Father, Lord of heaven and earth, because you have hidden these things from the wise and learned, and revealed them to little children.”
And he said: “Truly I tell you, unless you change and become like little children, you will never enter the kingdom of heaven.”
Paul makes it quite clear to us in his letter to the Romans:
That if you confess with your mouth, “Jesus is Lord,” and believe in your heart that God raised him from the dead, you will be saved. For it is with your heart that you believe and are justified, and it is with your mouth that you profess your faith and are saved.
Faith is non-transferrable.